Apparatus for recording on and playing back from magnetic tape (in particular video recordings), of the type in which a tape passes helicoidally in front of a slot separating two drums while magnetic heads carried by a disc of a rotor pass at high speed in front of the slot, is known. An apparatus of this type is described in the SMPTE Journal of December 1979, vol. 88, no. 12, p. 823 et seq (cf more particularly FIG. 13 with its rotating transformers).
Because of the extreme precision required for the movements of the magnetic heads, the shaft of the rotor is mounted in ball-bearings and subjected to rigorous machining operations after which it must be considered undismountable. However, the magnetic heads which move at a high linear speed (for example, 60 m/sec) have a shorter life than the mechanical assembly of the apparatus, and must therefore be changed during maintenance. The heads are therefore provided on a unit removable from the rotor. Rotating transformers permit the electric signals to be transmitted from the rotor to the fixed part of the apparatus and vice versa. In the known apparatus, the magnetic heads are connected by fixed connections to the rotating transformers of the rotor, such that these must be housed in the removable part of the rotor. As a result, the head-carrying part and the transformers are positioned in an overhung manner on the shaft of the rotor, ie outside the portion of the shaft between the bearings. This can result, at high rotational speeds, in problems of flexing of the shaft of the rotor. These problems are not generally perceptable for video apparatus, where the number of tracks necessary, and thus the number of transformers is very reduced.
On the other hand, for applications which require a high number of tracks and transformers (for example recording digital signals at high frequencies), it is no longer possible to mount the transformers in an overhung manner. It would be desirable to position them on the shaft between the bearings, on condition that it should be possible to establish an easily disconnectable connection between the magnetic heads and the transformers. such connection necessarily being of high density, given the restricted space available, and resistant to very high rotational speeds (for example from 4000 to 13000 r.p.m.).